Guidelines for Operating Traffic Signals During Low-Volume Conditions

摘要

The main objective of this research is to investigate the performance of flashing traffic signals as a device to control traffic periods with low traffic volumes, particularly during late night/early morning hours. First, the study identifies the main factors that affect the performance of flashing traffic signals. Next, it defines the main guidelines and precautions that should be considered when implementing flashing traffic signals in yellow/red or red/red modes, during late night/early morning hours. An extensive literature review is presented, which covers several case studies of flashing signal operation. In particular, three main aspects are considered in this review which are: safety and accident rates and types at intersections with flashing signal operation, motorists' comprehension to flashing traffic signals, and available guidelines for using flashing signal operation. Based on the review, the main factors that affect the operational performance of flashing traffic signals in its different modes are identified as follows: traffic volumes on the main and secondary approaches; number of lanes by type on each approach; average travel speed and speed limits; intersection geometrics and stopping sight distance; starting and ending time of flashing signal operation; land use in the surrounding area; traffic composition and existence of pedestrians and cyclists; familiarity of travelers with flashing signal operations; and availability of advisory signs.